if 3 boxes together weigh 90 pounds then each box weighs 30 pounds because 30×3=90 (30+30+30) and if you multiply 30×4 you get 120 because 30+30+30+30=120
Okay. The equation for a sphere's surface area is A = 4 * pi * r^2. Let's plug 5 in for r. I got 314 cm^2 is the surface area, but it always helps to double check work! Hope this helps!